Many techniques and devices exist for warming baby bottles and baby food. It is often the case that babies prefer to have their meals (milk, food, etc) warmed up to a temperature that is close to body temperature. Several common ways to warm a baby's bottle of milk (or formula, or other source of nourishment) are: run warm tap water over the bottle; heat a pot of water on the stove top, and put the bottle in the pot of warm water; heat the bottle (containing milk) in the microwave; or use a commercially-available food and/or bottle warmer.
Bottle warmers exist, have been produced, and are sold in an attempt to simplify the lives of parents, by making the process of warming baby's milk, formula, or food faster, easier, cleaner, safer, and simpler. The following types of bottle warmers exist today and are readily available:                Steam warmers: These devices boil a small amount of water, converting it to steam in a small warming chamber. The baby's bottle (containing milk, formula, or other food) is inserted into the warming chamber while the steam is being produced. The hot steam raises the temperature of the bottle and its contents. A representative example is disclosed in U.S. Pat. No. 6,861,618.        Water bath warmers: These devices use a cup-like chamber to hold a bath of water. The devices heat the water bath to a temperature sufficient for heating a baby bottle containing milk. The baby's bottle (containing milk, formula, or other food) is at least partially submerged in the bath of heated water. After some time, the contents of the bottle are warmed. A representative example is disclosed in U.S. Pat. No. 5,773,795 (directed to a warming device generally).        
There are many shortcomings to each of the existing approaches to warming babies' food and milk. Most of the existing techniques fail in at least one of the following ways: they are too slow; they are inconvenient because they require the use of dishes, pots and pans, large kitchen appliances, and other devices that need to be cleaner; they are unsafe because they can overheat the contents of the bottle if they are not closely monitored, and the bottle removed at just the right time; they are unhealthy because they are believed to damage some of the nutrients contained in milk, by exposing the milk to boiling (or higher) temperatures; they are inconvenient because they require constant monitoring; they are unsafe because they expose glass and plastic bottles to high temperatures that could be damaging to these materials, or that could cause these materials to release harmful chemicals into the air or the baby's food; they are unsafe because they can cause “hot spots” in heated liquids—regions of very high temperature that could burn a baby; or they are inconvenient because they require measuring or adding water with each use. Despite these substantial shortcomings in terms of safety and convenience, designs have continued to fall short for many years.